West Ham United's season was plunged into further turmoil last night when they were charged by the Premier League for breaching rules over the signings of Carlos Tevez and Javier Mascherano.

The club have vowed to "vigorously defend" themselves after being accused of breaching two regulations, U6 and U18, which forbid third-party player ownership from potentially influencing events at the destination club. The Premier League claims that when West Ham signed the Argentinian pair from Corinthians on deadline day last August they had agreements in place with the players' representatives, who could determine such factors as when the players were sold and when they were played.

Regulation U6 states: "No person may either directly or indirectly be involved in or have any power to determine or influence the management or administration of more than one club." Regulation U18 reads: "No club shall enter into a contract which enables any other party to that contract to require the ability materially to influence its policies or the performance of its teams in league matches."

A Premier League statement said: "It is the board's complaint that there were agreements in relation to both these transfers that enabled third parties to acquire the ability materially to influence the club's policies and/or the performance of its teams in League matches and/or the competitions set out in Rule E10. The board's view is this constitutes a breach of rule U18."

The Premier League alleges that West Ham were asked to provide details of their agreement with Tevez and Mascherano's representatives - they are linked with Media Sports Investment, formerly run by Kia Joorabchian - but these were not forthcoming.

The Premier League statement continued: "Furthermore at the time of the transfer agreements for both Carlos Tevez and Javier Mascherano, and until January 24 2007, West Ham United failed to disclose the third party agreements to the Premier League and/or deliberately withheld these agreements from the Premier League. The board's view is this constitutes a breach of rule B13, which states, 'In all matters and transactions relating to the League each club shall behave towards each other club and the League with the utmost good faith'."

The Premier League alleges that the problem was brought to light when Liverpool attempted to sign Mascherano at the beginning of the January transfer window. Liverpool hoped to sign him on the terms he was on at West Ham before the governing body intervened. West Ham then came forward with the required information. If they had submitted such information when the transfers were completed last year, the Premier League said, the duo would have been ineligible to play for West Ham.

The club, in their defence, will claim that Alan Pardew, then the manager, had full control over team selection, meaning U18 was not breached. The club will cite a precedent set in 1994, when Alan Sugar, then chairman of Tottenham Hotspur, had a 12-point deduction rescinded after arguing that the club's offences - making illegal payments to players - were committed by a former regime. The current West Ham ownership, an Icelandic consortium headed by Eggert Magnusson, did not sign Tevez and Mascherano.

"West Ham United has been notified of a disciplinary charge by the Premier League relating to the transfers of Javier Mascherano and Carlos Tevez and asked to respond within 14 days," said a West Ham statement. "In light of the legal advice received, the club will vigorously defend itself against the charge and provide a detailed response as requested by the Premier League in the time allowed."

West Ham's response will be heard by a three-person disciplinary commission, possible punishment ranging from a fine to a points deduction which would all but consign the Hammers to relegation.

Lost points

1890-91

Sunderland were deducted two points for fielding an ineligible player, Ned Doig, in a fixture against West Bromwich Albion. Doig was still registered with Blackburn. The sanction cost Sunderland two league places as they finished seventh, one point behind Blackburn

1967-68

Peterborough United were deducted 19 points in an irregular bonus scandal and were relegated to the Fourth Division

1990-91

Arsenal were deducted two points and Manchester United one after a brawl at Old Trafford. Arsenal went on to finish seven points clear of Liverpool at the top of the table. United finished sixth

1996-97

Middlesbrough were deducted three points for failing to fulfil a fixture at Blackburn Rovers. It cost them their place in the Premiership - they were relegated on the final day after managing only a draw at Leeds